Asset Display Screenlet for iOS

Requirements

• Xcode 9.3 or above
• iOS 11 SDK
• Liferay Portal 6.2 CE/EE, Liferay CE Portal 7.0/7.1, Liferay DXP 7.0+
• Liferay Screens Compatibility app (CE or EE/DXP). This app is preinstalled in Liferay CE Portal 7.0/7.1 and Liferay DXP 7.0+.

Compatibility

• iOS 9 and above

Xamarin Requirements

• Visual Studio 7.2
• Mono .NET framework 5.4.1.6

Features

Asset Display Screenlet can display an asset from a Liferay instance. The Screenlet can currently display Documents and Media files (DLFileEntry images, videos, audio files, and PDFs), blogs entries (BlogsEntry) and web content articles (WebContent).

Asset Display Screenlet can also display your custom asset types. See the delegate section of this document for details.

JSON Services Used

Screenlets in Liferay Screens call JSON web services in the portal. This Screenlet calls the following services and methods.

Service	Method	Notes
ScreensassetentryService (Screens compatibility plugin)	getAssetEntry	With entryId
ScreensassetentryService (Screens compatibility plugin)	getAssetEntry	With classPK and className
ScreensassetentryService (Screens compatibility plugin)	getAssetEntries	With entryQuery
ScreensassetentryService (Screens compatibility plugin)	getAssetEntries	With companyId, groupId, and portletItemName

Module

• None

Themes

• Default

The Default Theme uses different UI elements to show each asset type. For example, it displays images with UIImageView, and blogs with UILabel.

This Screenlet can also render other Screenlets:

• Images: Image Display Screenlet
• Videos: Video Display Screenlet
• Audio: Audio Display Screenlet
• PDFs: PDF Display Screenlet
• Blog entries: Blogs Entry Display Screenlet
• Web content: Web Content Display Screenlet

These Screenlets can also be used alone without Asset Display Screenlet.

Figure 1: Asset Display Screenlet using the Default Theme.

Offline

This Screenlet supports offline mode so it can function without a network connection. For more information on how offline mode works, see the tutorial on its architecture. Here are the offline mode policies that you can use with this Screenlet:

Policy	What happens	When to use
remote-only	The Screenlet loads the data from the Liferay instance. If a connection issue occurs, the Screenlet uses the listener to notify the developer about the error. If the Screenlet successfully loads the data, it stores it in the local cache for later use.	Use this policy when you always need to show updated data, and show nothing when there’s no connection.
cache-only	The Screenlet loads the data from the local cache. If the data isn’t there, the Screenlet uses the listener to notify the developer about the error.	Use this policy when you always need to show local data, without retrieving remote information under any circumstance.
remote-first	The Screenlet loads the data from the Liferay instance. If this succeeds, the Screenlet shows the data to the user and stores it in the local cache for later use. If a connection issue occurs, the Screenlet retrieves the data from the local cache. If the data doesn’t exist there, the Screenlet uses the listener to notify the developer about the error.	Use this policy to show the most recent version of the data when connected, but show an outdated version when there’s no connection.
cache-first	The Screenlet loads the data from the local cache. If the data isn’t there, the Screenlet requests it from the Liferay instance and notifies the developer about any errors that occur (including connectivity errors).	Use this policy to save bandwidth and loading time in case you have local (but probably outdated) data.

Required Attributes

• assetEntryId

Instead of assetEntryId, you can use both of these attributes:

• className
• classPK

If you don’t use the above attributes, you must use this attribute:

• portletItemName

Attributes

Attribute	Data type	Explanation
assetEntryId	number	The primary key of the asset.
className	string	The asset’s fully qualified class name. For example, a blog entry’s className is com.liferay.blogs.kernel.model.BlogsEntry. The className and classPK attributes are required to instantiate the Screenlet.
classPK	number	The asset’s unique identifier. The className and classPK attributes are required to instantiate the Screenlet.
portletItemName	string	The name of the configuration template you used in the Asset Publisher. To use this feature, add an Asset Publisher to one of your site’s pages (it may be a hidden page), configure the Asset Publisher’s filter (in Configuration → Setup → Asset Selection), and then use the Asset Publisher’s Configuration Templates option to save this configuration with a name. Use this name as this attribute’s value. If there is more than one asset in the configuration, the Screenlet displays only the first one.
assetEntry	Asset	The Asset object to display, selected from a list of assets. Note that if you use this attribute, the Screenlet doesn’t need to call the server.
autoLoad	boolean	Whether the asset automatically loads when the Screenlet appears in the app’s UI. The default value is true.
offlinePolicy	string	The offline mode setting. The default value is remote-first. See the Offline section for details.

Delegate

Asset Display Screenlet delegates some events to an object that conforms to the AssetDisplayScreenletDelegate protocol. This protocol lets you implement the following methods:

• - screenlet:onAssetResponse:: Called when the Screenlet receives the asset.

• - screenlet:onAssetError:: Called when an error occurs in the process. The NSError object describes the error.

• - screenlet:onConfigureScreenlet:: Called when the child Screenlet (the Screenlet rendered inside Asset Display Screenlet) has been successfully initialized. Use this method to configure or customize it. The example implementation here sets the child Blogs Entry Display Screenlet’s background color to gray:

    func screenlet(screenlet: AssetDisplayScreenlet, onConfigureScreenlet, 
        childScreenlet: BaseScreenlet?, onAsset asset: Asset) {
            if childScreenlet is BlogsEntryDisplayScreenlet {
                childScreenlet?.screenletView?.backgroundColor = UIColor.grayColor()
            }
    }
  

• - screenlet:onAsset:: Called to render a custom asset. The following example implementation renders a portal user (User). If the asset is a user, this method instantiates a custom UserProfileView to render that user:

    public func screenlet(screenlet: AssetDisplayScreenlet, onAsset asset: Asset) -> UIView? {
        if let type = asset.attributes["object"]?.allKeys.first as? String {
            if type == "user" {
                let view = NSBundle.mainBundle().loadNibNamed("UserProfileView", owner: self, 
                    options: nil)![0] as? UserProfileView
  
                view?.user = User(attributes: asset.attributes)
  
                return view
            }
        }
        return nil
    }